Waste to energy systems may be utilized to generate electricity, reduce a volume of waste or both. Such systems may rely on combustion to reduce a volume of waste while creating heat which may be used to generate steam and drive a turbine for generating electricity, for example. Gasification apparatus may also be used to generate synthetic gas from solid or liquid waste that may be used to fuel electrical generators, gas turbines, internal combustion engines, fuel cells, and combustion boilers, for example.
Waste to energy systems have been utilized for converting wet and dry wastes to electricity. Such waste to energy systems have been found to be particularly valuable in forward military applications where both facilities for waste disposal and fuel to drive electrical generators are in short supply. For example, waste to energy systems and methods may replace burn pits while reducing the use of liquid diesel fuel to generate electricity for military applications.
One example of a waste to energy system is a gasifier or reactor which inputs wet flammable waste and outputs synthetic gas among other things (e.g., oils, tar, ash and carbon black). Reactors may include rotating portions which receive the wastes and may be oriented horizontally but most often are configured as vertical columns and include various fixed bed or fluidized systems. Typical bed designs include fluidized bed, entrained bed, downdraft gasifier, and updraft gasifier. All of these configurations require, to varying degrees, that feedstock material be of relatively small particle size, reasonably homogeneous, and have a low moisture content (e.g., less than 10%).
Usually, any energy associated with the removal of excess water prior to a feedstock being input to a reactor has to be supplied to the process. Drying and combustion processes generally utilize natural gas or some other auxiliary fuel.
Thus, a need exists for improved systems and methods for converting a wet feedstock into a fuel.